Diptera is one of the biggest insect orders and displays a large diversity of visual adaptations. Similarly to other animals, the dipteran visual process is mediated by opsin genes. Although the diversity and function of these genes are well studied in key model species, a comprehensive comparative genomic study across the dipteran phylogeny is missing. Here we mined the genomes of 61 dipteran species, reconstructed the evolutionary affinities of 528 opsin genes, and determined the selective pressure acting in different species. We found that opsins underwent several lineage-specific events, including an independent expansion of Long Wave Sensitive opsins in flies and mosquitoes, and numerous family-specific duplications and losses. Both the Drosophila and the Anopheles complement are derived in comparison with the ancestral dipteran state. Molecular evolutionary studies suggest that gene turnover rate, overall mutation rate, and site-specific selective pressure are higher in Anopheles than in Drosophila. Overall, our findings indicate an extremely variable pattern of opsin evolution in dipterans, showcasing how two similarly aged radiations, Anopheles and Drosophila, are characterized by contrasting dynamics in the evolution of this gene family. These results provide a foundation for future studies on the dipteran visual system.

中文翻译：

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双翅目视蛋白基因的系统基因组学揭示了按蚊和果蝇的谱系特异性事件和对比进化动力学

双翅目是最大的昆虫目之一，具有多种视觉适应能力。与其他动物类似，双翅目视觉过程由视蛋白基因介导。尽管这些基因的多样性和功能在关键模式物种中得到了很好的研究，但缺乏对双翅目系统发育的全面比较基因组研究。在这里，我们挖掘了 61 个双翅目物种的基因组，重建了 528 个视蛋白基因的进化亲和力，并确定了作用于不同物种的选择压力。我们发现视蛋白经历了几个谱系特异性事件，包括苍蝇和蚊子中长波敏感视蛋白的独立扩展，以及许多特定于家族的重复和丢失。果蝇和按蚊补体都是与祖先的双翅目状态相比衍生的。分子进化研究表明，按蚊的基因更新率、总体突变率和位点特异性选择压力高于果蝇。总体而言，我们的研究结果表明双翅目视蛋白进化的模式极其多变，展示了两种年龄相似的辐射，按蚊和果蝇，如何通过该基因家族进化的对比动力学来表征。这些结果为今后对双翅目视觉系统的研究奠定了基础。其特点是该基因家族进化过程中的动态对比。这些结果为今后对双翅目视觉系统的研究奠定了基础。其特点是该基因家族进化过程中的动态对比。这些结果为今后对双翅目视觉系统的研究奠定了基础。